Hey @kanav-bansal 
Welcome to the Postman community! 
Your data from Scratchpad is safe.
Once signed in, you can Migrate all your Scratchpad data into a new Workspace using ⚙️ > Settings > Data > Migrate data menu option and contiune using Collections, Environments and all the other Postman features.
I’m going to close this topic as there are several similar questions that have already been asked.